/Engine/Source/Runtime/Engine/Public/PacketHandlers/StatelessConnectHandlerComponent.h
The different handshake packet types
namespace UE { namespace Net { enum EHandshakePacketType { InitialPacket = 0, Challenge = 1, Response = 2, Ack = 3, RestartHandshake = 4, RestartResponse = 5, VersionUpgrade = 6, Last = VersionUpgrade, } } }